Overbanking preventive means



Sept. 17, 1957 K. H. SCHOENROCK OVERBANKING PREVENTIVE MEANS Filed May 17, 1956 IN VENTOR ATTORNEY United States Patent ()fiiice 2,806,344 OVERBANKING PREVENTIVE MEANS Application May 17, 1956, Serial No. 585,569 Claims. (Cl. 58-107) This invention relates to an improvement for electric watches and provides means for preventing overbanking of the balance wheel.

In electric watches in which there is no pallet fork and banking pins, there is a possibility that should the watch receive a shock at the exact moment when the balance wheel has swung through the extent of its are that the shock will advance the balance wheel through a greater angular displacement, even to the point of having the balance wheel energized again and carried through a second cycle. To prevent this it is necessary that after energization, the balance wheel be limited in motion to approximately 225.

It is the object of the present invention to provide a mechanism which will not disturb the ordinary motion of I the balance wheel but which will when the motion exceeds 225 of arc, from impulse position, apply a braking action to the balance wheel to prevent overbanking.

It is a still further object of the present invention to provide a pin located in the path of expansion of the hairspring, which said pin will be contacted by the outermost coil of the hairspring when the balance wheel exceeds 225 of are from the impulse position, and that such pin being pivotally mounted will move from contact with the hairspring to bring a braking action to bear on the balance wheel, thus stopping rotation of the balance wheel past the 225 angle.

It is a still further object of the invention to provide a pivoted member carrying a pin, said pin being located in the path of expansion of the hairspring, said member also carrying a bent wire adapted to be swung into contact with the rim of the balance wheel to provide a braking action upon movement of the pin through contact with the hairspring.

The invention is illustrated in the accompanying drawing in which:

Figure l is a perspective view of a portion of an electric watch showing the balance wheel and hairspring assembly With the improvement constituting this invention mounted thereon.

Figure 2 is a vertical section of that portion of the watch shown in Figure 1.

Figure 3 shows the balance wheel and hairspring assembly with the overbanking preventive means in inoperative position.

Figure 4 is a view similar to Figure 3 showing the overbanking preventive means in balance wheel braking position.

Referring particularly to the drawings a pillar plate is shown with a balance wheel 12 having a coil 14, counterbalancing screws 16 and a hairspring 18. A balat its upper end. Attached to the balance cock is a pin 24 on which is pivotally mounted a member 26.

The member 26 carries a pin 28 adapted to be engaged by the outermost coil of the hairspring 18 and a second pin 30 engaging the edge of the balance cock at 32 to limit the pivotal motion of the member 26 and withhold it from the normal expansion path of the hairspring. A small coil spring 34 in the nature of a hairspring is attached to the pivoted member by a stud 36 and serves 2,806,344 Patented Sept. 17, 1957 to swing the pivoted member so that the stop is in engagement with the balance cock 20.

Attached to the pivoted member is a braking spring 38 having its end terminated in a slight curve and in close proximity to the outer rim of the balance wheel.

The balance wheel is impulsed by magnets 40 acting on the coil 14 when the coil passes between said magnets 40 and the shunt 42 to thus energize the coil at practically the position shown in Figures 1 and 3. The desired motion of the coil is over and less than 225 which would bring the coil at the end of its impulse at approxiber 26 about the pivot 24 and moves the braking wire 38 into contact with the counterbalancing screws 16 at a point 40. The action of the braking wire on the balance wheel is very light but suificient to arrest the motion of the balance wheel and to definitely prevent any overbanking or the balance wheel from moving into the position shown in Figure 3 where it will be again impulsed by the magnets and coil.

It will be noted that the action takes place only during the motion of the balance wheel in a counterclockwise direction. Motion in the other direction is, of course, under the influence of the hairspring and the hairspring contracts to a tightly wound position which would prevent any overbanking in this direction.

What is claimed is:

1. An overbanking preventive means for an electric watch having a balance whel and hairspring assembly comprising, pivotally mounted means positioned in the path of hairspring expansion, and means governed by said pivoted means for restricting the balance wheel motion.

2. An overbanking preventive means for an electric watch having a balance wheel and hairspring assembly comprising, a movable pin located in the expansion path of the hairspring and adapted to be moved by contact with said hairspring, and means actuated by movement of the pin for restricting the motion of the balance wheel.

3. An overbanking preventive means for an electric watch having a balance cock supporting a balance wheel and hairspring assembly comprising, a plate pivotally supported on said balance cook, a pin carried by said plate and positioned 1n the path of the hairspring expansion to swing the plate about the pivotal support, means carried by the plate and moving into contact with the rim of the balance wheel upon the pivotal movement of the plate to restrict the movement of the balance wheel.

4. An overbanking preventive means for an electric watch as in claim 3, wherein the means carried by the plate consists of a spring bent to contact the outer rim of the balance wheel upon pivotal movement of said plate.

5. An overbanking preventive means for an electric watch having a balance cock supporting a balance wheel and hairspring assembly comprising, a plate pivotally supported on said balance cock, a hairspring connected No references cited. 

